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1931 4 running VERY HOT

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  • #16
    Thanks everyone. All your comments are very helpful. Just reset everything and took it out for a quick test ride. It seems...... to be running cooler. It's still feels a bit weak but I'm sure at some point I'll figure it out. Keep the comments coming and again, thank you.

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    • #17
      Just my guess - on my Henderson, I would check for intake leaks and timing. If it is retarded a bit, they well get hot quick ! One tooth off can make a big difference in timing and heat.

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      • #18
        Howdy sir,

        May want to confirm the health of your magneto. Weak output mimics your description of leaning out mixture to eliminate black smoke only to have the machine run hot at speed. Unlike battery/distributor set ups having a constant voltage output at the coil, a magneto generates its own voltage to make a spark and its output increases with rpm. A weak spark at idle or low rpm with a carb leaned down to accommodate then can go to lean as revs and magneto output increases closer to its desired output. If closing your spark plug gaps progressively down from the recommended .025 - .030 gap makes for a better or more predictably running motor you have a mag output or condenser issue.

        To clarify on recommending ignition fully retarded when make idle screw adjustment this applies to both the mechanical stop at the bellcrank as well as your low speed needle. You want a steady even idle, not the loping 8 stroking idle that results from trying to refine this adjustment with the ignition advanced. When making that high speed adjustment where momentarily cracking the throttle is required to eliminate backfiring of leanness then, yes, have ignition advanced. There are lots of YouTube videos of idling Fours to give you and idea of what you’re aiming for.
        Cheerio,
        Peter
        #6510
        1950 Vincent - A Red Rapide Experience

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